Crosslinkable polyurea polymers

ABSTRACT

The invention relates to novel crosslinkable prepolymers of formula (1), wherein the variables have the meanings given in the claims, to homo- or co-polymers obtainable therefrom by crosslinking and to mouldings, such as, especially, contact lenses, made from those homo- or co-polymers.

The present invention relates to novel crosslinkable polyureas, to aprocess for the preparation thereof and to the use thereof in themanufacture of mouldings, especially ophthalmic mouldings, for examplecontact lenses.

The present invention relates to prepolymers of formula

Q—CP—Q  (1),

wherein

Q is an organic radical that comprises at least one crosslinkable group,and

CP is a bivalent copolymer fragment consisting of the segments A, B andT, wherein:

A is a bivalent radical of formula

—RN—A₁—NR′—  (2a),

 wherein A₁ is the bivalent radical of a polyalkylene glycol or is alinear or branched alkylene radical having from 2 to 24 carbon atoms andeach of R and R′ independently of the other is hydrogen or unsubstitutedor substituted C₁-C₆alkyl or, in the case of the amino group thatterminates the copolymer fragment, may also be a direct, ring-formingbond;

T is a bivalent radical of formula

 wherein X is a bivalent aliphatic, cycloaliphatic,aliphatic-cycloaliphatic, aromatic, araliphatic oraliphatic-heterocyclic radical; and

B is a radical of formula

—R₁N—B₁—NR₁′—  (2b),

 wherein each of R₁ and R₁′ independently of the other has the meaningsgiven above for R, B₁ is a bivalent aliphatic, cycloaliphatic,aliphatic-cycloaliphatic, aromatic or araliphatic hydrocarbon radicalthat is interrupted by at least one amine group of formula

 and R₂ is hydrogen, a radical Q mentioned above or a radical of formula

Q—CP′—  (4),

 wherein

Q is as defined above, and CP′ is a bivalent copolymer fragmentindependently consisting of at least two of the above-mentioned segmentsA, B and T; with the provisos

that in the copolymer fragments CP and CP′ a segment A or B is followedby a segment T in each case;

that in the copolymer fragments CP and CP′ a segment T is followed by asegment A or B in each case;

that the radical Q in formulae (1) and (4) is bonded to a segment A or Bin each case; and that the N atom in formula (3) is bonded to a segmentT when R₂ is a radical of formula (4).

Q is, for example, an olefinically unsaturated, copolymerisable radicalthat is bonded to the amine nitrogen —NR—, —NR′—, —NR₁— or —NR₁′— in asuitable manner, for example directly, by way of a functional group orby way of a bridge member, or that together with —NR—, —NR′—, —NR₁— or—NR₁′— forms a cyclic ring; in the latter case, R, R′, R₁ or R₁′ is adirect, ring-forming bond.

The radical Q corresponds, for example, to a radical R₃ mentionedhereinbelow or to a radical of formula

wherein Q₁ is, for example, a radical of formula

and wherein

Z is linear or branched C₂-C₁₂alkylene,

R₃ is an olefinically unsaturated copolymerisable radical having from 2to 24 carbon atoms which may be further substituted,

W is a C₂-C₁₂alkylene radical, phenylene radical or C₇-C₁₂aralkyleneradical, each of R₄ and R₄′ independently of the other is hydrogen,C₁-C₄alkyl or halogen,

R₅ is a bivalent aliphatic, cycloaliphatic, aliphatic-cycloaliphatic,aromatic or araliphatic hydrocarbon radical,

R₆ is hydrogen or C₁-C₄alkyl,

each of alk and alk′ independently of the other is a linear or branchedC₁-C₁₂alkylene radical,

each of m and n independently of the other is the number 0 or 1,

Z″ is C₁-C₆alkylene and

P₁ independently is a radical of the above-mentioned formula (5) whereinQ₁ is a radical of the above formula (5a), (5b), (5c) or (5e) and nindependently is as defined above.

Z is preferably linear or branched C₂-C₈alkylene, more preferably linearC₂-C₆alkylene and most preferably linear C₂-C₄alkylene. In a preferredembodiment of the invention, Z is 1,3-propylene or, especially,1,2-ethylene.

Suitable substituents on the olefinic C₂-C₂₄ radical R₃ are, forexample, C₁-C₄alkoxy, halogen, phenyl or carboxy.

R₃ is, for example, a radical of formula

wherein p is the number 0 or 1,

R₇ is hydrogen, C₁-C₄alkyl or halogen,

each of R₈ and R₉ independently of the other is hydrogen, C₁-C₄alkyl,phenyl, carboxy or halogen, and

Z′ is linear or branched C₁-C₁₂alkylene or unsubstituted or C₁-C₄alkyl-or C₁-C₄alkoxy-substituted phenylene or C₇-C₁₂aralkylene.

When Z′ is a phenylene radical, it is, for example, unsubstituted ormethyl- or methoxy-substituted 1,2-, 1,3- or 1,4-phenylene. Preferably,Z′ as a phenylene radical is 1,3- or 1,4-phenylene.

When Z′ is an aralkylene radical, it is, for example, unsubstituted ormethyl- or methoxy-substituted benzylene, wherein the methylene group isbonded to the amine nitrogen in each case. Preferably, Z′ as anaralkylene radical is the 1,3- or 1,4-phenylenemethylene radical,wherein the methylene group is bonded to the amine nitrogen —NH— in eachcase.

Z′ is preferably unsubstituted or methyl- or methoxy-substitutedphenylene or phenylene-methylene or C₁-C₁₂alkylene, more preferably 1,3-or 1,4-phenylene or C₁-C₆alkylene, especially C₁-C₂alkylene and mostpreferably methylene.

p is the number 1 or, preferably, the number 0.

R₇ is preferably hydrogen, methyl or chlorine and most preferablyhydrogen or methyl.

Each of R₈ and R₉ independently of the other is preferably hydrogen,carboxy, chlorine, methyl or phenyl. In a preferred embodiment of theinvention, R₈ is hydrogen, chlorine, methyl or phenyl and R₉ is hydrogenor carboxy. Most preferably, R₈ and R₉ are each hydrogen.

Examples of suitable radicals R₃ are vinyl, 2-propenyl, allyl,2-butenyl, o-, m- or p-vinyl-phenyl, styryl, 2-carboxyvinyl,2-chloro-2-carboxyvinyl, 1,2-dichloro-2-carboxyvinyl,1,2-dimethyl-2-carboxyvinyl and 2-methyl-2-carboxyvinyl.

Especially preferred radicals R₃ correspond to formula (6) wherein p is0, R₇ is hydrogen or methyl, R₈ is hydrogen, methyl, chlorine or phenyland R₉ is hydrogen or carboxy.

Other especially preferred radicals R₃ correspond to the above formula(6) wherein p is 1, Z′ is 1,3- or 1,4-phenylene or C₁-C₆alkylene,especially C₁-C₂alkylene, R₇ is hydrogen or methyl and R₈ and R₉ areeach hydrogen.

Z″ is preferably C₁-C₄alkylene, especially methylene or1,1-dimethylmethylene.

One group of suitable radicals Q corresponds to the above formula (5)wherein n is 0 and Q₁ is a radical of the above formula (5a) wherein mis 0 and for R₃ the meanings and preferences given above apply.

A second group of suitable radicals Q corresponds to the above formula(5) wherein n is 1 and Q₁ is a radical of the above formula (5a) whereinm is 0 and for R₃ and Z the meanings and preferences given above apply.

A further group of suitable radicals Q corresponds to the above formula(5) wherein n is 1 and Q₁ is a radical of the above formula (5a) whereinm is 1 and for R₃ and Z the meanings and preferences given above apply.

A further group of suitable radicals Q corresponds to the above formula(5) wherein n is 0 and Q₁ is a radical of the above formula (5e) whereinfor R₃ and Z″ the meanings and preferences given above apply.

In formulae (5b) and (5c), the variable W is preferably a C₂-C₆alkyleneradical or a 1,3- or 1,4-phenylene radical and most preferably aC₂-C₃alkylene radical. Each of R₄ and R₄′ independently of the other ispreferably hydrogen, methyl or chlorine. Most preferably, each of R₄ andR₄′ independently of the other is hydrogen or methyl.

In formula (5d), R₅ is, for example, linear or branched C₃-C₁₈alkyleneor unsubstituted or C₁-C₄alkyl- or C₁-C₄alkoxy-substitutedC₆-C₁₀arylene, C₇-C₁₈aralkylene, C₆-C₁₀ arylene-C₁-C₂alkylene-C₆-C₁₀arylene, C₃-C₈cycloalkylene, C₃-C₈cycloalkylene-C₁-C₆alkylene,C₃-C₈cycloalkylene-C₁-C₂alkylene-C₃-C₈cycloalkylene,C₁-C₆alkylene-C₃-C₈cycloalkylene-C₁-C₆alkylene or analiphatic-heterocyclic radical comprising at least one hydantoin group.

R₅ as alkylene is preferably a linear or branched C₃-C₁₄alkyleneradical, more preferably a linear or branched C₄-C₁₂alkylene radical andmost preferably a linear or branched C₆-C₁₀-alkylene radical. Somepreferred alkylene radicals are 1,4-butylene, 2,2-dimethyl-1,4-butylene,1,5-pentylene, 2,2-dimethyl-1,5-pentylene, 1,6-hexylene, 2,2,3- or2,2,4-trimethyl-1,5-pentylene, 2,2-dimethyl-1,6-hexylene, 2,2,3- or2,2,4- or 2,2,5-trimethyl-1,6-hexylene, 2,2-dimethyl-1,7-heptylene,2,2,3- or 2,2,4- or 2,2,5 or 2,2,6-trimethyl-1,7-heptylene,1,8-octylene, 2,2-dimethyl-1,8-octylene and 2,2,3- or 2,2,4- or 2,2,5-or 2,2,6- or 2,2,7-trimethyl-1,8-octylene.

When R₅ is arylene, it is, for example, naphthylene or especiallyphenylene, each of which may be substituted, for example, by C₁-C₄alkylor by C₁-C₄alkoxy. Preferably, R₅ as arylene is 1,3- or 1,4-phenylenethat is substituted by C₁-C₄alkyl or by C₁-C₄alkoxy in theortho-position to at least one linkage site. Examples of substitutedarylene are 1-methyl-2,4-phenylene, 1,5-dimethyl-2,4-phenylene,1-methoxy-2,4-phenylene and 1-methyl-2,7-naphthylene.

R₅ as aralkylene is preferably naphthylalkylene and most preferablyphenylalkylene. The alkylene group in aralkylene contains preferablyfrom 1 to 12, more preferably from 1 to 6 and most preferably from 1 to4 carbon atoms. Most preferably, the alkylene group in aralkylene ismethylene or ethylene. Some examples are 1,3- or 1,4-benzylene,naphth-2-yl-7-methylene, 6-methyl-1,3- or -1,4-benzylene and6-methoxy-1,3- or -1,4-benzylene.

When R₅ is cycloalkylene, it is preferably C₅-C₆cycloalkylene and mostpreferably cyclohexylene that is unsubstituted or substituted by methyl.Some examples are 1,3-cyclobutylene, 1,3-cyclopentylene, 1,3- or1,4-cyclohexylene, 1,3- or 1,4-cycloheptylene, 1,3- or 1,4- or1,5-cyclooctylene, 4-methyl-1,3-cyclopentylene,4-methyl-1,3-cyclohexylene, 4,4-dimethyl-1,3-cyclohexylene, 3-methyl- or3,3-dimethyl-1,4-cyclohexylene, 3,5-dimethyl-1,3-cyclohexylene and2,4-dimethyl-1,4-cyclohexylene.

When R₅ is cycloalkylene-alkylene, it is preferablycyclopentylene-C₁-C₄alkylene and especially cyclohexylene-C₁-C₄alkylene,each unsubstituted or mono- or poly-substituted by C₁-C₄alkyl,especially methyl. More preferably, the group cycloalkylene-alkylene iscyclohexylene-ethylene and, most preferably, cyclohexylene-methylene,each unsubstituted or substituted in the cyclohexylene radical by from 1to 3 methyl groups. Some examples are cyclopent-1-yl-3-methylene,3-methyl-cyclopent-1-yl-3-methylene,3,4-dimethyl-cyclopent-1-yl-3-methylene,3,4,4-trimethyl-cyclopent-1-yl-3-methylene, cyclohex-1-yl-3- or-4-methylene, 3- or 4- or 5-methyl-cyclohex-1-yl-3- or -4-methylene,3,4- or 3,5-dimethyl-cyclohex-1-yl-3 or -4-methylene and 3,4,5- or3,4,4- or 3,5,5-trimethyl-cyclohex-1 -yl-3- or -4-methylene.

When R₅ is alkylene-cycloalkylene-alkylene, it is preferablyC₁-C₄alkylene-cyclopentylene -C₁-C₄alkylene and especiallyC₁-C₄alkylene-cyclohexylene-C₁-C₄alkylene, each unsubstituted or mono-or poly-substituted by C₁-C₄alkyl, especially methyl. More preferably,the group alkylene-cycloalkylene-alkylene isethylene-cyclohexylene-ethylene and, most preferably, ismethylene-cyclohexylene-methylene, each unsubstituted or substituted inthe cyclohexylene radical by from 1 to 3 methyl groups. Some examplesare cyclopentane-1,3-dimethylene, 3-methyl-cyclopentane-1,3-dimethylene,3,4-dimethyl-cyclopentane-1,3-dimethylene,3,4,4-trimethyl-cyclopentane-1,3-dimethylene, cyclohexane-1,3- or-1,4-dimethylene, 3- or 4- or 5-methyl-cyclohexane-1,3- or-1,4-dimethylene, 3,4- or 3,5-dimethylcyclohexane-1,3- or-1,4-dimethylene, 3,4,5- or 3,4,4- or 3,5,5-trimethyl-cyclohexane-1,3-or -1,4-dimethylene.

R₅ as C₃-C₈cycloalkylene-C₁-C₂alkylene-C₃-C₈cycloalkylene orC₆-C₁₀arylene-C₁-C₂alkylene -C₆-C₁₀arylene is preferablyC₅-C₆cycloalkylene-methylene-C₅-C₆cycloalkylene orphenylene-methylene-phenylene, each of which may be unsubstituted orsubstituted in the cycloalkyl or phenyl ring by one or more methylgroups.

When R₅ is an aliphatic-heterocyclic radical containing hydantoingroups, it may correspond, for example, to formula

wherein R₁₄ and R₁₄′ are each C₁-C₆alkylene, preferably C₂-C₄alkyleneand especially C₂-C₃alkylene, R₁₅, R₁₅ and R₁₆′ are each independentlyof the others hydrogen, C₁-C₆alkyl or C₅-C₇cycloalkyl, preferably areeach independently of the others hydrogen or C₁-C₄alkyl and especiallyare each methyl, R₁₅ C is C₁-C₁₂alkylene and preferably C₁-C₆-alkyleneand R₁₆ and R₁₆′ are each independently of the other hydrogen orC₁-C₄alkyl and preferably hydrogen or methyl.

The radical R₅ in formula (5d) has a symmetrical or, preferably, anasymmetrical structure.

A preferred group of radicals Q₁ of formula (5d) comprises those whereinR₅ is linear or branched C₆-C₁₀alkylene; cyclohexylene-methylene orcyclohexylene-methylene-cyclohexylene each unsubstituted or substitutedin the cyclohexyl moiety by from 1 to 3 methyl groups; or phenylene orphenylene-methylene-phenylene each unsubstituted or substituted in thephenyl moiety by methyl.

The bivalent radical R₅ is derived preferably from a diisocyanate andmost preferably from a diisocyanate selected from the group isophoronediisocyanate (IPDI), toluylene-2,4-diisocyanate (TDI),4,4′-methylenebis(cyclohexyl isocyanate),1,6-diisocyanato-2,2,4-trimethyl-n-hexane (TMDI), methylenebis(phenylisocyanate), methylenebis(cyclohexyl-4-isocyanate) and hexamethylenediisocyanate (HMDI).

Each of the radicals alk and alk′ independently of the other ispreferably a C₂-C₈alkylene radical, more preferably a C₂-C₄alkyleneradical and most preferably the 1,2-ethylene radical.

R₆ is preferably methyl or especially hydrogen.

P₁ is a radical of the above formula (5) wherein 01 is a radical of theabove formula (5a), (5b) or (5c), and wherein for the variablescontained therein the meanings and preferences given above apply in eachcase.

P₁ is preferably a radical of the above formula (5) wherein Q₁ is aradical of the above formula (5a), and most preferably is a radical offormula (5′) or (5′″) given below.

When Q is a radical R₃, the meaning and preferences given above for R₃apply in each case.

When Q together with —N—R—, —N—R′—, —NR₁′—or —NR₁′—forms a cyclic ringcomprising at least one crosslinkable group, it is in each case, forexample, a radical of formula

wherein each of R₄ and R₄′ is as defined above and preferably each ismethyl.

Especially preferred radicals Q correspond to formula

wherein for R₅ the meanings and preferences given above apply in eachcase.

Especially preferred as the radical Q are radicals of the above formulae(5′) and (5′″).

Each of R and R′ independently of the other is, for example, hydrogen orunsubstituted or, for example, hydroxy- or C₁-C₄alkoxy-substitutedC₁-C₆alkyl, preferably hydrogen or unsubstituted or hydroxy-substitutedC₁-C₄alkyl, more preferably hydrogen, C₁-C₂alkyl or hydroxy-C₁-C₂alkyland most preferably hydrogen. The radicals R and R′ may be different or,preferably, identical.

When the radical A_(i) is a polyalkylene glycol radical, it maycorrespond, for example, to formula

—Alk—[(O—CH₂—CH₂)_(r)—(O—CHR₁₀—CHR₁₁)_(s)—(O—CHR₁₂—CHR₁₃)_(t)]—O—Alk′—  (7)

wherein each of (Alk) and (Alk)′ independently of the other is a linearor branched, unsubstituted or, for example, hydroxy-substitutedC₁-C₁₂alkylene radical; one of the radicals R₁₀ and R₁₁ is hydrogen andthe other is methyl; one of the radicals R₁₂ and R₁₃ is hydrogen and theother is C₂-C₄alkyl; and each of r, s and t independently of the othersis a number from 0 to 100, the sum of (r+s+t) being from 1 to 100.

In formula (7), each of (Alk) and (Alk′) independently of the other ispreferably linear or branched C₂-C₈alkylene, more preferably linear orbranched C₂-C₆alkylene and most preferably linear or branchedC₂-C₄alkylene. Examples of especially preferred radicals (Alk) and(Alk′) are 1,2-ethylene, 1,2-propylene and 1,3-propylene. The radicals(Alk) and (Alk′) may be different or, preferably, identical.

Each of r, s and t independently of the others is preferably a numberfrom 0 to 80, the sum of (r+s+t) being from 2 to 80. Most preferably,each of r, s and t independently of the others is a number from 0 to 50,the sum of (r+s+t) being from 4 to 50 and especially from 8 to 50.

Of the radicals R₁₂ and R₁₃ one is hydrogen and the other is preferablyethyl.

Preferred embodiments of the -polyalkylene glycol radicals A₁ are:

(i) a radical of formula (7) wherein each of (Alk) and (Alk′)independently of the other is linear or branched C₂-C₆alkylene, t is 0,and each of r and s independently of the other is a number from 0 to100, the sum of (r+s) being from 1 to 100; preferably from 0 to 80, thesum of (r+s) being from 2 to 80; and most preferably from 0 to 50, thesum of (r+s) being from 4 to 50 or especially from 8 to 50;

(ii) a radical of formula (7) wherein (Alk) and Alk′) are identical andeach is linear or branched C₂-C₄alkylene, s and t are each 0 and r is anumber from 1 to 100, preferably from 2 to 80, more preferably from 4 to50 and most preferably from 8 to 50.

When A is an alkylene radical, it is preferably an unsubstituted orhydroxy-substituted C₂-C₁₂alkylene radical, more preferably anunsubstituted or hydroxy-substituted C₂-C₈-alkylene radical and mostpreferably a C₂-C₆alkylene radical, which may in each case be branchedor, preferably, linear. Examples of suitable alkylene segments A are1,2-ethylene, 1,2- or 1,3-propylene, 2-hydroxy-1,3-propylene,1,4-butylene, 1,5-pentylene and 1,6-hexylene.

Preferred embodiments of the segments A according to the invention are:

(i) a bivalent radical of formula (2a) wherein R and R′ are eachhydrogen or C₁-C₄alkyl and A₁ is a bivalent polyalkylene glycol radicalof formula

—Alk—[(O—CH₂—CH₂)_(r)—(O—CHR₁₀—CHR₁₁)_(s) ]—O—Alk′—  (7a)

 wherein (Alk) and (Alk′) are identical and each is linear or branchedC₂-C₆alkylene, one of the radicals R₁₀ and R₁₁ is hydrogen and the otheris methyl, and each of r and s independently of the other is a numberfrom 0 to 80 and especially from 0 to 50, the sum of (r+s) being from 2to 80, preferably from 4 to 50 and most preferably from 8 to 50;

(ii) a bivalent radical of formula (2a) wherein R and R′ are eachhydrogen and A₁ is a bivalent polyalkylene glycol radical of formula

—Alk—(O—CH₂CH₂)_(r)—O—Alk′—  (7b)

 wherein (Alk) and (Alk′) are identical and each is linear or branchedC₂-C₄alkylene, and r is a number from 4 to 50 and especially from 8 to50;

(iii) a bivalent radical of formula (2a) wherein R and R′ are eachhydroxy-substituted C₁-C₄-alkyl and A₁ is a C₂-C₆alkylene radical.

The compositions of block copolymers, e.g. the polymer fragments offormulae (7) and (7a), mentioned in the text always correspond in eachcase to a mean statistical composition. This means that block copolymerradicals having alternating units, having repeating identical units orhaving a mixture of alternating and repeating units are included,provided that the ultimate mean statistical composition complies withthe specified parameters.

The prepolymers of the invention may have uniform segments A or,alternatively, two or more structurally different segments A, forexample 2 or 3 or, preferably, 2 different segments A.

With regard to the segments T of formula (2) according to the invention,for X independently the meanings and preferences given above for R₅apply. Accordingly, in a preferred embodiment of the invention, X isderived from an aliphatic, cycloaliphatic, aliphatic-cycloaliphatic,aromatic or araliphatic diisocyanate, especially from a diisocyanateselected from the group isophorone diisocyanate (IPDI),toluylene-2,4-diisocyanate (TDI), methylenebis(cyclohexyl isocyanate),1,6-diisocyanato-2,2,4-trimethyl-n-hexane (TMDI), methylenebis(phenylisocyanate), methylenebis(cyclohexyl isocyanate) and hexamethylenediisocyanate (HMDI).

The prepolymers of the invention may have uniform segments T or,alternatively, two or more structurally different segments T.Preferably, the prepolymers contain uniform segments T.

Each of R₁ and R₁′ independently of the other is preferably hydrogen orunsubstituted or, for example, hydroxy- or C₁-C₄alkoxy-substitutedC₁-C₆alkyl, preferably hydrogen or unsubstituted or hydroxy-substitutedC₁-C₄alkyl, more preferably hydrogen, C₁-C₂alkyl or hydroxy-C₁-C₂alkyland most preferably hydrogen. The radicals R₁ und R₁′ may be differentor, preferably, identical. In a preferred embodiment of the invention,R, R′, R₁ and R₁′ each have the same meaning and are especiallyhydrogen.

The radical B₁ may be, for example, linear or branched C₃-C₂₄alkylene orunsubstituted or C₁-C₄alkyl-substituted C₆-C₁₀arylene, C₇-C₁₈aralkylene,C₆-C₁₀arylene-C₁-C₂alkylene-C₆-C₁₀-arylene, C₃-C₈cycloalkylene,C₃-C₈cycloalkylene-C₁C₆alkylene,C₃-C₈cycloalkylene-C₁C₂-alkylene-C₃-C₈cycloalkylene orC₁-C₆alkylene-C₃-C₈cycloalkylene-C₁-C₆alkylene, each of which isinterrupted by at least one group —N(R₂)— of formula (3), preferably byfrom 1 to 3 or especially 1 or 2 identical or different groups offormula (3), more preferably by 1 or 2 identical groups of formula (3)or most preferably by 1 group of formula (3).

Preferably, the radical B₁ is a linear or branched C₄-C₂₄alkyleneradical that is interrupted by from 1 to 3 groups, preferably 1 or 2groups and especially by one group of the above formula (3).

Especially preferred as the radical B₁ is linear or branched alkylenehaving from 3 to 14 or especially from 4 to 12 carbon atoms that isinterrupted by one group of formula (3).

When R₂ is a radical 0 or a radical of formula (4), then, for thesegments A, B and T contained therein and for the variable Q, themeanings, preferences and conditions given above apply in each case.

One group of preferred radicals B₁ corresponds to formula

wherein each of alk*, alk** and alk*** independently of the others is aC₂-C₁₂alkylene radical, preferably a C₂-C₆alkylene radical and mostpreferably a C₂-C₄alkylene radical; I is the number 0 or 1 andespecially the number 0 and for R₂ and R₂′ independently the meaningsand preferences given above for R₂ apply in each case.

The prepolymers according to the invention may have uniform segments Bor, alternatively, two or more structurally different segments B.Preferably, the prepolymers contain one or more different segments B offormula

wherein for R₁, R₁′, R₂, R₂′, alk*, alk**, alk*** and I the meanings andpreferences given above apply in each case. When the prepolymers containdifferent segments B, they are preferably in the form of a mixture of 2,3 or more different segments of the above formula (8a) that areidentical with regard to R₁, R₁′, alk*, alk**, alk*** and I but differwith regard to the variables R₂ and/or R₂′. One example is a mixture oftwo or more different segments of formula (8a) wherein I is 0 in eachcase, R₁, R₁′, alk* and alk** are in each case identical and have one ofthe meanings given above, and wherein R₂ in the different segments hasin each case a meaning that differs from the others, selected from thegroup consisting of radical -CP′, radical -Q and hydrogen.

Alternatively, there also come into consideration, for example,different segments B that differ with regard to alk*, alk**, R₁ and/orR₁′.

The number of segments A in the polymer fragments CP and CP′ ispreferably greater than the number of segments B. The number of segmentsA and B in the polymer fragments CP and CP′ is preferably in a ratio of1:0.01 to 0.5, preferably 1:0.05 to 0.4 and most preferably 1:0.1 to0.25.

The average molecular weight of the polymer fragments CP is, forexample, in a range of approximately from 350 to 25,000, preferably from500 to 10,000 and most preferably from 1000 to 5000.

In a preferred embodiment of the invention, the polymer fragment CP isterminated on both sides by a segment A. It is furthermore preferredthat any polymer fragments CP′ that are present are also terminated by asegment A.

The prepolymers of formula (1) can be prepared in a manner known per se,for example by reacting together a compound of formula

a compound of formula

O═C═N—X—N═C═O  (11), and

a compound of formula

wherein for A₁, R, R′, R₁, R₁′ and X the meanings and preferences givenabove apply in each case and for B₁′ independently the meanings andpreferences given above for B₁ apply, except that R₂ in the amine groupsof formula (3) is in each case hydrogen, and reacting the copolymer soobtainable of formula

H—CP*—H  (1a),

wherein CP* independently has the meanings given above for CP, exceptthat R₂ in the segments B is hydrogen or a radical —CP′—NR″H and R″independently has the meanings given above for R, with a compound offormula

Y—Q₁  (13),

wherein Q₁ is as defined above and Y is, for example, halogen, e.g.bromine or especially chlorine; a carboxyl group —COOH; a suitablecarboxyl group derivative, e.g. a group —COOR₁₉, wherein R₁₉ is, forexample, phenyl or C₁-C₄alkyl, —CO—Hal, wherein Hal is halogen, e.g.—COBr or especially —COCl; or a group —N═C═O, or wherein Q₁ togetherwith Y forms a heterocyclic compound containing, for example, an oxygenatom as hetero atom.

The compounds of formulae (10), (11) and (12) are known compounds or canbe obtained by methods known perse. Examples of suitable compounds offormula (10) are N,N′-dihydroxyalkyl-alkylenediamines, e.g.N,N′-dihydroxyethyl-C₂-C₆alkylenediamines, or preferablybis-aminoalkylene-polyalkylene glycols of various average molecularweights, e.g. so-called Jeffamines having an average molecular weightof, for example, approximately from 200 to 5000, e.g.bis(2-aminopropyl)polyethylene glycol 500 to approximately 2000 orbis(2-aminoethyl)polyethylene glycol 1000 to approximately 3400.Suitable diisocyanates of formula (11) are, for example, isophoronediisocyanate (IPDI), toluylene-2,4-diisocyanate (TDI),methylenebis(cyclohexyl isocyanate),1,6-diisocyanato-2,2,4-trimethyl-n-hexane (TMDI), methylenebis(phenylisocyanate), methylenebis(cyclohexyl isocyanate) and hexamethylenediisocyanate (HMDI). Examples of suitable compounds of formula (12) arepolyamines, e.g. symmetrical or asymmetrical dialkylenetriamines ortrialkylenetetramines, e.g. diethylenetriamine,N-2′-aminoethyl-1,3-propylenediamine, N,N-bis(3-aminopropyl)-amine,N,N-bis(6-aminohexyl)amine or triethylenetetramine. It is possible touse in the process, for example, one compound each of formulae (10), (11) and (12) or two or more different compounds of formula(e) (10), (11)and/or (12), there being obtained in the latter case product mixtures ofseveral copolymers of formula (1a). One advantageous variant comprises,for example, reacting two or more different compounds of formula (10)with one compound each of formulae (11) and (12).

The reaction of the diamine of formula (10), the polyamine of formula(12) and the diisocyanate of formula (11) is advantageously carried outin an aqueous or aqueous-organic medium. A suitable medium has beenfound to be especially a mixture of water and a readily water-solubleorganic solvent, e.g. an alkanol, such as methanol, ethanol orisopropanol, a cyclic ether, such as tetrahydrofuran, or a ketone, suchas acetone. An especially suitable reaction medium is a mixture of waterand a readily water-soluble solvent having a boiling point of from 50 to85° C., preferably from 50 to 70° C., especially a water/-tetrahydrofuran or a water/acetone mixture.

The reaction temperature in the first reaction step of the process is,for example, from −5 to 50° C., preferably from 0 to 30° C. and mostpreferably from 2 to 10° C.

The reaction times may vary within wide limits, a time of approximatelyfrom 1 to 10 hours, preferably from 2 to 8 hours and most preferably 2to 3 hours having proved practicable.

The stoichiometry in the reaction of the compounds of formulae (10),(11) and (12) is advantageously so selected that the number of molarequivalents of the amine groups contained in the compounds of formulae(10) and (12) is greater than the number of molar equivalents of theisocyanato groups contained in the compounds of formula (11). Forexample, the excess of amine groups in the compounds of formulae (10)and (12) in relation to the isocyanato groups in the compounds offormula (11) is from 0.02 to 1 molar equivalent, preferably from 0.05 to0.8 molar equivalent, more preferably from 0.1 to 0.6 molar equivalentand most preferably from 0.2 to 0.4 molar equivalent.

It is furthermore preferred that the diamine of formula (10) is used ina molar excess in relation to the polyamine of formula (12). A molarratio of the diamine of formula (10) to the polyamine of formula (12) offrom 1:0.01 to 1:0.5, preferably from 1:0.05 to 1:0.4 and mostpreferably from 1:0.1 to 1:0.3 has proved especially advantageous.

If, as is preferred, the compound of formula (12) is a triamine, thecompounds of formulae (10), (12) and (11) are used, for example, in amolar ratio of 1 equivalent of compound of formula (10), from 0.05 to0.4 equivalent of compound of formula (12) and from 0.7 to 1.6equivalents of compound of formula (11); preferably 1 equivalent ofcompound of formula (10), from 0.1 to 0.3 equivalent of compound offormula (12) and from 0.85 to 1.35 equivalents of compound of formula(11); and most preferably 1 equivalent of compound of formula (10),approximately 0.2 equivalent of compound of formula (12) and from 1.1 to1.2 equivalents of compound of formula (11).

The isolation and purification of the copolymers of formula (1a)obtainable according to the first reaction step can be carried out in amanner known per se, for example by extraction, distillation,filtration, ultrafiltration or chromatographic methods.

The copolymers of formula (1a) are novel and the invention relates tothem also. They are generally liquid or readily meltable compounds thatare predominantly water-soluble. The average molecular weight of thecopolymers of formula (1a) may vary within wide limits, but isadvantageously, for example, from 350 to 25,000, preferably from 500 to10,000 and most preferably from 1000 to 5000.

The reaction solution containing a copolymer of formula (1a) which isobtainable according to the first reaction step can be reacted with acompound of formula (13) to form a prepolymer of formula (1) withoutbeing purified or after purification by means of a customary method,e.g. by means of ultrafiltration. Advantageously, for example, from 0.1to 1.5 molar equivalents, preferably from 0.2 to 1 molar equivalent andmost preferably from 0.25 to 0.6 molar equivalent of compound of formula(13), based in each case on 1 molar equivalent of compound of formula(1a), are used in the process.

The compounds of formula (13) are in most cases known or can be preparedby methods known per se. Examples of preferred compounds of formula (13)are allyl chloride or bromide, acryloyl chloride, methacryloyl chloride,cinnamic acid chloride, maleic acid anhydride, mono- or di-methylmaleicacid anhydride, 2-isocyanatoethyl acrylate or 2-isocyanatoethylmethacrylate.

A group of novel compounds of formula (13) corresponds to formula

wherein for R₅, R₆, P₁, alk and alk′ the meanings and preferences givenabove apply in each case.

Preferred as compounds of formula (14) are those of formula

wherein for R₅ the meanings and preferences given above apply in eachcase.

The compounds of formula (14) can be prepared in a manner known per se,for example by reacting a diisocyanate, which may, if desired, bemono-masked, of formula

O═C═N—R₅—N═C═O  (15),

wherein R₅ is as defined above, with a compound of formula

wherein R₆, P₁, alk and alk′ are each as defined above, in an inertsolvent. It is especially advantageous to use here diisocyanates havingisocyanate groups of differing reactivity since the formation of isomersand diadducts can thereby be substantially suppressed. The differingreactivity can be brought about, for example, by steric hindrance. Inaddition, the differing reactivity can also be achieved by masking anisocyanate group in the diisocyanate.

Masking agents are known from urethane chemistry. They may be, forexample, phenols (cresol, xylenol), lactams (ε-caprolactam), oximes(acetoxime, benzophenone oxime), active-H methylene compounds (diethylmalonate, ethyl acetoacetate), pyrazoles or benzotriazoles. Maskingagents are described, for example, by Z. W. Wicks, Jr. in Progress inOrganic Coatings, 9 (1981), pages 3 to 28.

Suitable inert solvents for the reaction of the compound of formula (15)with a compound of formula (16) are aprotic, preferably polar, solvents,for example hydrocarbons (petroleum ether, methylcyclohexane, benzene,toluene, xylene), halogenated hydrocarbons (chloroform, methylenechloride, trichloroethane, tetrachloroethane, chlorobenzene), ethers(diethyl ether, dibutyl ether, ethylene glycol dimethyl ether,diethylene glycol dimethyl ether, tetrahydrofuran, dioxane), ketones(acetone, dibutyl ketone, methyl isobutyl ketone), carboxylic acidesters and lactones (ethyl acetate, butyrolactone, valerolactone),alkylated carboxylic acid amides (N,N-dimethylacetamide,N-methylpyrrolidone), nitrites (acetonitrile), sulfones and sulfoxides(dimethyl sulfoxide, tetramethylenesulfone). Polar solvents arepreferably used. The reactants are advantageously used in equimolarquantities. The reaction temperature may be, for example, from 0 to 200°C. When catalysts are used, the temperatures may advantageously be inthe range of from 0 to 50° C., preferably at room temperature. Suitablecatalysts are, for example, metal salts, such as alkali metal salts ofcarboxylic acids, tertiary amines, for example (C₁-C₆alkyl)₃N(triethylamine, tri-n-butylamine), N-methylpyrrolidine,N-methylmorpholine, N,N-dimethylpiperidine, pyridine and1,4-diazabicyclooctane. Tin salts have been found to be especiallyeffective, especially alkyltin salts of carboxylic acids, for exampledibutyltin dilaurate and tin dioctoate. The isolation and purificationof the compounds prepared is carried out according to known methods, forexample by means of extraction, crystallisation, recrystallisation orchromatographic purification methods.

The compounds of formula (15) are known or can be prepared by methodsknown per se. The compounds of formula (16) are novel and the inventionrelates to them also. They can be prepared, for example, by reactingapproximately 1 molar equivalent of a compound of formula

HO—alk—NH—alk′—NH—R₆  (17),

wherein R₆, alk and alk′ are each as defined above, with approximately 2molar equivalents of a compound of formula

Y—Q₁′  (13a),

wherein Y is as defined above and Q₁′ is a radical of the above formula(5a), (5b) or (5c), preferably (5a).

The reaction of the copolymers of formula (1a) with a compound offormula (13) and the reaction of the compound of formula (17) with acompound of formula (13a) are carried out, where the compounds offormulae (13) and (13a) are carboxylic acid derivatives and, especially,carboxylic acid halides, under the conditions that are customary foramide formation, for example at temperatures of, for example, from 0 to80° C., preferably from 0 to 50° C. and most preferably from 0 to 25°C., in a dipolar aprotic solvent, e.g. tetrahydrofuran, dioxane, DMSOetc., or in a mixture of water and one of the mentioned solvents, in thepresence of a base, e.g. an alkali metal hydroxide, and, whereapplicable, in the presence of a stabiliser. Suitable stabilisers are,for example, 2,6-dialkylphenols, hydroquinone derivatives, e.g.hydroquinone or hydroquinone monoalkyl ethers, or N-oxides, e.g.4-hydroxy-2,2,6,6-tetramethyl-piperidin-1-yl. The reaction times mayvary within wide limits, a period of, for example, from 30 minutes to 12hours, preferably from 1 to 6 hours and especially from 2 to 3 hours,generally having been found practicable.

Where the compounds of formulae (13) and (13a) are isocyanates, thereaction thereof with a copolymer of formula (1a) or with a compound offormula (17), respectively, can be carried out under the conditionsgiven above for the reaction of the compounds of formulae (10), (11) and(12).

Where the compounds of formulae (13) and (13a) are alkyl halides, thereaction thereof with a copolymer of formula (1a) or with a compound offormula (17), respectively, can be carried out, for example, under theconditions that are customary for the alkylation of amines.

Where the compounds of formulae (13) and (13a) are heterocycliccompounds, they may be, for example, cyclic acid anhydrides, for examplemaleic acid anhydride, which can be converted in a manner known per sewith a copolymer of formula (1a) or with a compound of formula (17),respectively, into a corresponding copolymer containing imide groups.

The prepolymers of the invention are crosslinkable, but areuncrosslinked or, at least, substantially uncrosslinked; in addition,they are stable, that is to say spontaneous crosslinking as a result ofhomopolymerisation does not take place.

The prepolymers of the invention are advantageously liquid or readilymeltable or water-soluble; their average molecular weight may varywithin wide limits. An average molecular weight of, for example, from350 to 25,000, preferably from 500 to 10,000 and most preferably from1000 to 5000 has proved advantageous for the prepolymers of theinvention.

The prepolymers of formula (1) can be isolated and purified in a mannerknown per se, for example by extraction, precipitation, crystallisation,recrystallisation, filtration, ultrafiltration, chromatography, reverseosmosis or dialysis, with ultrafiltration being especially preferred. Bymeans of that purification procedure the prepolymers of the inventioncan be obtained in extremely pure form, for example as solventlessliquids or melts or as concentrated aqueous solutions that are free orat least substantially free of reaction products, such as salts, andstarting materials or other non-polymeric constituents.

The preferred purification method for the prepolymers of the invention,ultrafiltration, can be carried out in a manner known per se. It ispossible to carry out the ultrafiltration repeatedly, for example fromtwo to ten times. Alternatively, the ultrafiltration can also be carriedout continuously until the desired degree of purity is reached. Thedegree of purity selected may, in principle, be as high as desired andis preferably set in such a manner that the content of undesiredconstituents in the prepolymers is, for example, ≦0.001% and morepreferably ≦0.0001% (1 ppm). The prepolymers may contain in addition,for example as a consequence of their synthesis, constituents that areacceptable from a physiological viewpoint, e.g. sodium chloride, suchconstituents advantageously being present in an amount of ≦1%,preferably ≦0.1%, and most preferably ≦0.01%.

The prepolymers of formula (1) according to the invention are, asalready mentioned above, crosslinkable in a controlled and extremelyeffective manner, especially by photo-cross-linking.

The present invention further relates, therefore, to a polymer that canbe obtained by photo-crosslinking of a prepolymer of formula (1), in theabsence or presence of an additional vinyl comonomer. These crosslinkedpolymers are water-insoluble.

In the photo-crosslinking, a photoinitiator capable of initiatingfree-radical crosslinking is suitably added. Examples thereof will befamiliar to the person skilled in the art, suitable photoinitiators thatmay specifically be mentioned being benzoin methyl ether,1-hydroxy-cyclohexylphenyl ketone, Darocure 1173 or Irgacure types. Thecrosslinking can then be brought about by actinic radiation, e.g. UVlight, or ionising radiation, e.g. gamma rays or X-rays.

The photo-polymerisation can be carried out without the addition of asolvent, for example when the prepolymer is a liquid or readily meltableprepolymer, or takes place in a suitable solvent. Suitable solvents arein principle all solvents that dissolve the polymers according to theinvention and the vinyl comonomers which may be additionally used, e.g.water, alcohols, such as lower alkanols, e.g. ethanol or methanol,carboxylic acid amides, such as dimethylformamide, or dimethylsulfoxide, and mixtures of suitable solvents, e.g. mixtures of waterwith an alcohol, e.g. a water/ethanol or a water/methanol mixture.

The photo-crosslinking is preferably effected under solventless orsubstantially solventless conditions or directly from an aqueoussolution of the prepolymers according to the invention which can beobtained as a result of the preferred purification step,ultrafiltration, optionally after the addition of an additional vinylcomonomer. For example, photo-cross-linking of an approximately 15 to90% aqueous solution can be carried out.

The process for the preparation of the crosslinked polymers of theinvention comprises, for example, photo-crosslinking a prepolymer offormula (1), especially in substantially pure form, that is to say, forexample, after single or repeated ultrafiltration, under solventless orsubstantially solventless conditions or in solution, especially inaqueous solution, in the absence or presence of an additional vinylcomonomer.

The vinyl comonomer that can additionally be used according to theinvention in the photo-crosslinking may be hydrophilic or hydrophobic ormay be a mixture of a hydrophobic and a hydrophilic vinyl monomer.Suitable vinyl monomers include especially those which are customarilyused in the manufacture of contact lenses. The expression “hydrophilicvinyl monomer” is understood to mean a monomer that typically producesas homopolymer a polymer that is water-soluble or capable of absorbingat least 10% by weight water. Analogously, the expression “hydrophobicvinyl monomer” is understood to mean a monomer that typically producesas homopolymer a polymer that is water-insoluble or capable of absorbingless than 10% by weight water.

In general, approximately from 0.01 to 80 units of a typical vinylcomonomer react per prepolymer unit of formula (1).

The proportion of vinyl comonomers, if used, is preferably from 0.5 to80 units per prepolymer unit of formula (1), especially from 1 to 30units of vinyl comonomer per prepolymer unit of formula (1) and mostpreferably from 5 to 20 units per prepolymer unit of formula (1).

It is also preferred to use a hydrophobic vinyl comonomer or a mixtureof a hydrophobic vinyl comonomer with a hydrophilic vinyl comonomer, themixture containing at least 50% by weight of a hydrophobic vinylcomonomer. In that manner, the mechanical properties of the polymer canbe improved without the water content being appreciably reduced. Inprinciple, however, both conventional hydrophobic vinyl comonomers andconventional hydrophilic vinyl comonomers are suitable forcopolymerisation with a prepolymer of formula (1).

Suitable hydrophobic vinyl comonomers include, without the followingbeing an exhaustive list, C₁-C₁₈alkyl acrylates and methacrylates,C₃-C₁₈alkylacrylamides and -methacrylamides, acrylonitrile,methacrylonitrile, vinyl-C₁-C₁₈alkanoates, C₂-C₁₈alkenes,C₂-C₁₈haloalkenes, styrene, C₁-C₆alkylstyrene, vinyl alkyl ethers inwhich the alkyl moiety has from 1 to 6 carbon atoms,C₂-C₁₀perfluoroalkyl acrylates and methacrylates or correspondinglypartially fluorinated acrylates and methacrylates,C₃-C₁₂perfluoroalkyl-ethyl-thiocarbonylaminoethyl acrylates andmethacrylates, acryloxy- and methacryloxy-alkylsiloxanes,N-vinylcarbazole, C₁—C₁₂alkyl esters of maleic acid, fumaric acid,itaconic acid, mesaconic acid and the like.

Preferred are, for example, C₁-C₄alkyl esters of vinylically unsaturatedcarboxylic acids having from 3 to 5 carbon atoms or vinyl esters ofcarboxylic acids having up to 5 carbon atoms.

Examples of suitable hydrophobic vinyl comonomers include methylacrylate, ethyl acrylate, propyl acrylate, isopropyl acrylate,cyclohexyl acrylate, 2-ethylhexyl acrylate, methyl methacrylate, ethylmethacrylate, propyl methacrylate, vinyl acetate, vinyl propionate,vinyl butyrate, vinyl valerate, styrene, chloroprene, vinyl chloride,vinylidene chloride, acrylonitrile, 1-butene, butadiene,methacrylonitrile, vinyltoluene, vinyl ethyl ether,perfluorohexylethyl-thiocarbonylaminoethyl methacrylate, isobornylmethacrylate, trifluoroethyl methacrylate, hexafluoroisopropylmethacrylate, hexafluorobutyl methacrylate,tris-trimethylsilyloxy-silyl-propyl methacrylate,3-methacryloxypropylpentamethyldisiloxane andbis(methacryloxypropyl)tetramethyldisiloxane.

Suitable hydrophilic vinyl comonomers include, without the followingbeing an exhaustive list, hydroxy-substituted lower alkyl acrylates andmethacrylates, acrylamide, methacrylamide, lower alkylacrylamide and-methacrylamide, ethoxylated acrylates and methacrylates,hydroxy-substituted lower alkylacrylamides and methacrylamides,hydroxy-substituted lower alkyl vinyl ethers, sodium ethylenesulfonate,sodium styrenesulfonate, 2-acrylamido-2-methylpropanesulfonic acid,N-vinylpyrrole, N-vinylsuccinimide, N-vinylpyrrolidone, 2- or4-vinylpyridine, acrylic acid, methacrylic acid, amino- (the term“amino” also including quaternary ammonium), mono-lower alkylamino- ordi-lower alkylamino-lower alkyl acrylates and methacrylates, allylalcohol and the like. Preferred are, for example, hydroxy-substitutedC₂-C₄alkyl (meth)acrylates, five- to seven-membered N-vinyl lactams,N,N-di-C₁-C₄alkyl-(meth)acrylamides and vinylically unsaturatedcarboxylic acids having a total of from 3 to 5 carbon atoms.

Examples of suitable hydrophilic vinyl comonomers include hydroxyethylmethacrylate, hydroxyethyl acrylate, acrylamide, methacrylamide,dimethylacrylamide, allyl alcohol, vinylpyridine, vinylpyrrolidine,glycerol methacrylate, N-(1,1-dimethyl-3-oxobutyl)-acrylamide and thelike.

Preferred hydrophobic vinyl comonomers are methyl methacrylate and vinylacetate. Preferred hydrophilic vinyl comonomers are 2-hydroxyethylmethacylate, N-vinylpyrrolidone and acrylamide.

The prepolymers of the invention can be processed in a manner known perse to form mouldings, especially contact lenses, for example by carryingout the photo-crosslinking of the prepolymers of the invention in asuitable contact lens mould. The invention further relates, therefore,to mouldings that substantially consist of a prepolymer of theinvention. Further examples of mouldings of the invention, apart fromcontact lenses, are biomedical or special ophthalmic mouldings, e.g.intraocular lenses, eye dressings, mouldings for use membranes forcontrolling diffusion, photo-structurable films for information storage,or photoresist materials, e.g. membranes or mouldings for etch resistsor screen print resists.

A preferred process for the manufacture of mouldings comprises thefollowing steps:

a) introducing into a mould a prepolymer of formula (1) that is liquidat room temperature or readily meltable and that is substantially freeof solvents, in the absence or presence of an additional vinyl comonomerand/or photoinitiator,

b) causing photo-crosslinking for a period of ≦60 minutes,

c) opening the mould so that the moulding can be removed from the mould.

Another preferred process for the manufacture of mouldings comprises thefollowing steps:

a) preparing a substantially aqueous solution of a water-solubleprepolymer of formula (1) in the absence or presence of an additionalvinyl comonomer and/or photoinitiator,

b) introducing the resulting solution into a mould,

c) causing photo-crosslinking for a period of ≦60 minutes,

d) opening the mould so that the moulding can be removed from the mould.

In the preferred processes described above, it is especially preferredin each case to introduce the prepolymer in the absence of an additionalvinyl comonomer. It is further preferred to introduce the prepolymerinto the mould in the presence of a photoinitiator.

For introducing the prepolymers of the invention into a mould it ispossible to use methods known per se, such as, especially, conventionalmetering in, e.g. dropwise introduction. Suitable vinyl comonomers, ifpresent, will be the aforementioned comonomers in the amounts given. Thevinyl comonomers that may be present are advantageously mixed with theprepolymer of the invention first and then introduced into the mould.

Appropriate moulds are made, for example, of polypropylene. Suitablematerials for re-usable moulds are, for example, quartz, sapphirecrystal or metals.

If the mouldings to be manufactured are contact lenses, they can bemanufactured in a manner known per se, for example in a conventionalspin-casting mould as described, for example, in U.S. Pat. 3,408,429, orby the full-mould process in a static mould as described, for example,in U.S. Pat. No. 4 347 198.

The photo-crosslinking can be brought about in the mould, for example byactinic radiation, e.g. UV light, or ionising radiation, e.g. gamma raysor X-rays.

As already mentioned, the photo-crosslinking is advantageously carriedout in the presence of a photoinitiator capable of initiatingfree-radical crosslinking. The photoinitiator is advantageously added tothe prepolymers of the invention before introduction into the mould,preferably by mixing the polymers and the photoinitiator with oneanother. The amount of photoinitiator may be selected within widelimits, an amount of up to 0.05 g/g of polymer and especially of up to0.003 g/g of polymer having proved beneficial.

It is to be stressed that, according to the invention, the crosslinkingmay take place in a very short time, for example in ≦60 minutes,advantageously in ≦20 minutes, especially in ≦10 minutes, moreespecially in ≦5 minutes, even more especially in ≦1 minute and mostespecially in ≦30 seconds.

Opening of the mould so that the moulding can be removed from the mouldcan be carried out in a manner known per se.

If the moulding manufactured according to the invention is a contactlens and the latter has been manufactured under solventless conditionsfrom a previously purified prepolymer of the invention, then it isnormally unnecessary for the removal of the moulding to be followed bypurification steps, e.g. extraction, because the prepolymers used do notcontain any undesired low-molecular-weight constituents; consequently,the crosslinked product also is free or substantially free of suchconstituents and subsequent extraction can be dispensed with. Thecontact lens can accordingly be converted into a ready-for-use contactlens directly in conventional manner by hydration. Suitable forms ofhydration capable of producing ready-for-use contact lenses with a widevariety of water contents are known to the person skilled in the art.The contact lens is swelled, for example, in water, in an aqueous saltsolution, especially in an aqueous salt solution having an osmolarity ofapproximately from 200 to 450 milliosmol in 1000 ml (unit: mosm/l),preferably approximately from 250 to 350 mosm/l and especiallyapproximately 300 mosm/l, or in a mixture of water or an aqueous saltsolution with a physiologically tolerable polar organic solvent, forexample glycerol. Swelling of the prepolymer in water or in aqueous saltsolutions is preferred.

The aqueous salt solutions used for the hydration are advantageouslysolutions of physiologically tolerable salts, such as buffer saltscustomary in the field of contact lens care, e.g. phosphate salts, orisotonising agents customary in the field of contact lens care, such as,especially, alkali metal halides, e.g. sodium chloride, or solutions ofmixtures thereof. An example of an especially suitable salt solution isa synthetic, preferably buffered, lachrymal fluid that has been matchedto natural lachrymal fluid with regard to pH value and osmolarity, e.g.an unbuffered or preferably buffered, for example phosphatebuffer-buffered, sodium chloride solution the osmolarity and pH value ofwhich correspond to the osmolarity and pH value of human lachryrnalfluid.

The hydration fluids defined above are preferably pure, that is to sayfree or substantially free of undesired constituents. Most preferably,the hydration fluid is pure water or a synthetic lachrymal fluid asdescribed above.

If the moulding manufactured according to the invention is a contactlens and the latter has been manufactured from an aqueous solution of apreviously purified prepolymer of the invention, the crosslinked productalso will not contain any troublesome impurities. There is normally noneed, therefore, for subsequent extraction. Since the crosslinking iscarried out in a substantially aqueous solution, there is also no needfor subsequent hydration. In accordance with an advantageous embodiment,therefore, the contact lenses obtainable by this process aredistinguished by the fact that they are suitable for use as intendedwithout extraction. The expression “use as intended” is understood inthis context to mean especially that the contact lenses can be insertedinto the human eye.

The contact lenses obtainable according to the invention have a range ofunusual and extremely advantageous properties. Among those properties,there may be mentioned, for example, their excellent compatibility withthe human cornea, which is due to a balanced ratio of water content,oxygen permeability and mechanical properties. The contact lenses of theinvention furthermore have a high dimensional stability. Even afterautoclaving at, for example, approximately 120° C. no changes in shapecan be detected.

Attention may also be drawn to the fact that the contact lenses of theinvention, that is to say especially those comprising a crosslinkedpolymer of a prepolymer of formula (1), can be manufactured in a verysimple and efficient manner compared with the prior art. This is due toseveral factors. Firstly, the starting materials can be obtained orprepared at little cost. Secondly, there is the advantage that theprepolymers are surprisingly stable and can therefore be subjected tohigh-grade purification. For crosslinking, therefore, it is possible touse a polymer that requires virtually no subsequent purification, suchas, especially, laborious extraction of unpolymerised constituents.Furthermore, the crosslinking can be carried out under solventlessconditions or in aqueous solution, with the result that subsequentsolvent exchange and the hydration step are not necessary. Finally, thephotopolymerisation takes place within a short time, so that themanufacturing process of the contact lenses of the invention can be madeextraordinarily economic from that point of view also.

All of the advantages mentioned above apply, of course, not only tocontact lenses but also to other mouldings of the invention. The sum ofthe various advantageous aspects in the manufacture of the mouldings ofthe invention results in the mouldings of the invention being especiallysuitable as mass-produced articles, such as, for example, contact lensesthat are worn for a short period and then replaced by new lenses.

In the Examples which follow, amounts are by weight, unless specifiedotherwise, and temperatures are given in degrees Celsius.

EXAMPLE 1 Preparation of a Polyurea

300 g of tetrahydrofuran (THF), 160 g of water, 95.7 g ofbis(2-aminopropyl)polyethylene glycol 800, 65.68 g ofbis(2-aminopropyl)polyethylene glycol 500 and 4.13 g ofdiethylenetriamine are placed in a glass apparatus. At an internaltemperature of approximately from 3 to 6° C., a solution of 48.91 g ofisophorone diisocyanate in 35 g of THF is added dropwise with intensivestirring and the reaction mixture is left to react at from 2 to 6° C.for approximately a further 25 minutes. The internal temperature is thenincreased over a period of approximately 3 hours to from 25 to 30° C.and, when the reaction is complete, the THF is distilled off underreduced pressure using a rotary evaporator. The aqueous solution is thenpurified at room temperature by means of filtration over a 0.45 μmfilter and via ultrafiltration using a 1 kD filter. The purifiedsolution is concentrated and the residue is dried for approximately 1hour at 70° C./0.1 mbar. A yellowish, highly viscous polyurea isobtained, having 0.31 mol. equiv. of amine/g.

EXAMPLE 2 Preparation of a Crosslinkable Polyurea

Analogously to Example 1, 95.7 g of bis(2-aminopropyl)polyethyleneglycol 800, 65.68 g of bis(2-aminopropyl)polyethylene glycol 500 and4.13 g of diethylenetriamine are placed in 300 ml of THF and 160 ml ofwater, and a solution of 48.91 g of isophorone diisocyanate in 160 ml ofTHF is added dropwise. The reaction mixture is left to react at from 3to 8° C. for approximately a further 105 minutes and then 50 ml of 2Nsodium hydroxide solution and 50 mg of4-hydroxy-2,2,6,6-tetramethylpiperidin-1-yl are added thereto and 7.24 gof acryloyl chloride are added dropwise over a period of approximately 8minutes. After a further 100 minutes, 3 g of solid sodium hydroxide areadded to the reaction mixture and then a further 7.24 g of acryloylchloride are added dropwise. This is followed by stirring forapproximately 2.5 hours at approximately from 2 to 18° C. and by removalof the THF from the reaction mixture by distillation. The aqueoussolution is then purified at room temperature by means of filtrationover a 0.45 μm filter and via ultrafiltration using a 1 kD filter. Theresulting clear, colourless solution is concentrated at 60° C./30 to 100mbar until the solids content is 45.7% by weight. For analyticalpurposes, a sample is lyophilised and analysed. The double bond contentof the dried polymer is 0.36 equivalent of double bond/g.

EXAMPLE 3 Manufacture of a Contact Lens

9.2 mg of a photoinitiator (Irgacure® 2959) are dissolved in 13.06 g ofa 35% polyurea solution prepared according to Example 2, and theresulting solution is purified by filtration over a 0.45 μm filter.Then, the polyurea solution provided with the photoinitiator isintroduced into a contact lens mould and irradiated for 7.6 seconds,corresponding to a dose of 18 mJ/cm². Colourless transparent lenseshaving the following physical data are obtained: water content 68%,elongation at tear >210%, modulus 1.228 MPa.

EXAMPLES 4-11

Transparent contact lenses having good all-round properties are alsoobtained by following the procedure described in Examples 2 and 3 andreacting together, instead of the components used therein, the compoundslisted in the following Table, in the amounts indicated.

TABLE Ex. Compound of Compound of Compound of Compound of No formula(10) formula (12) formula (11) formula (13)  4 1 mol. equiv. 0.27 mol.equiv. 1.2 mol. equiv. 0.41 mol. PEG 500/PEG DETA HMDI equiv. 800 (1:1)IEM  5 1 mol. equiv. 0.37 mol. equiv. 1.1 mol. equiv. 0.91 mol. PEG 1900DETA MBCYI equiv. IEM  6 1 mol. equiv. 0.2 mol. equiv. 1.1 mol. equiv.0.4 mol. equiv. PEG 500/PEG DETA TMDI A-Cl 800 (1:1)  7 1 mol. equiv.0.15 mol. equiv. 1.1 mol. equiv. 0.4 mol. equiv. PEG 500/PEG TETA IPDIA-Cl 800 (7:3)  8 1 mol. equiv. 0.2 mol. equiv. 1.1 mol. equiv. 0.4 mol.equiv. PEG 800 DETA IPDI CA-Cl  9 1 mol. equiv. 0.2 mol. equiv. 1.1 mol.equiv. 0.4 mol. equiv. PEG 800/ DETA IPDI A-Cl BHEED (1:1) 10 1 mol.equiv. 0.2 mol. equiv. 1.1 mol. equiv. 0.4 mol. equiv. PEG 800 DETA IPDIMA 11 1 mol. equiv. 0.2 mol. equiv. 1.1 mol. equiv. 0.4 mol. equiv. PEG800 DETA IPDI MIB-Cl

In the Table, PEG 500, PEG 800 and PEG 1900 denotebis(2-aminopropyl)polyethylene glycol 500, 800 and 1900; BHEED denotesN,N′-bis(2-hydroxyethyl)ethylenediamine; DETA denotesdiethylenetriamine; TETA denotes triethylenetetramine; HMDI denoteshexamethylene-1,6-diisocyanate; MBCYI denotes4,4′-methylene-bis(cyclohexyl isocyanate); TMDI denotes1,6-diisocyanato-2,2,4-trimethyl-n-hexane; IPDI denotes isophoronediisocyanate; IEM denotes 2-isocyanatoethyl methacrylate; A-Cl denotesacrytoyl chloride; CA-Cl denotes cinnamic acid chloride; MA denotesmaleic acid anhydride; and MIB-Cl denotes 4-maleimidyl-benzoyl chloride.

What is claimed is:
 1. A prepolymer of formula Q—CP—Q  (1), wherein Q isan organic radical that comprises at least one crosslinkable group, andCP is a bivalent copolymer fragment consisting of the segments A, B andT, wherein: A is a bivalent radical of formula —RN—A₁—NR′—  (2a), wherein A₁ is the bivalent radical of a polyalkylene glycol or is alinear or branched alkylene radical having from 2 to 24 carbon atoms andeach of R and R′ independently of the other is hydrogen or unsubstitutedor substituted C₁-C₆alkyl or, in the case of the amino group thatterminates the copolymer fragment, may also be a direct, ring-formingbond; T is a bivalent radical of formula

 wherein X is a bivalent aliphatic, cycloaliphatic,aliphatic-cycloaliphatic, aromatic, araliphatic oraliphatic-heterocyclic radical; and B is a radical of formula A—R₁N—B₁—NR₁′—  (2b),  wherein each of R₁ and R₁′ independently of theother has the meanings given above for R, B₁ is a bivalent atiphatic,cycloaliphatic, aliphatic-cycloaliphatic, aromatic or araliphatichydrocarbon radical that is interrupted by at least one amine group offormula

R₂ is hydrogen, a radical Q mentioned above or a radical of formulaQ—CP′—  (4),  wherein Q is as defined above, and CP′ is a bivalentcopolymer fragment independently consisting of at least two of theabove-mentioned segments A, B and T; with the provisos that in thecopolymer fragments CP and CP′ a segment A or B is followed by a segmentT in each case; that in the copolymer fragments CP and CP′ a segment Tis followed by a segment A or B in each case; that the radical Q informulae (1) and (4) is bonded to a segment A or B in each case; andthat the N atom in formula (3) is bonded to a segment T when R₂ is aradical of formula (4).
 2. A prepolymer according to claim 1, wherein Qis (i) an olefinically unsaturated to copolymerisable radical R₃ havingfrom 2 to 24 carbon atoms which may be further substituted, or (ii) agroup of formula

 wherein Q₁ is a radical of formula

 and wherein Z is linear or branched C₁-C₁₂alkylene, R₃ is anolefinically unsaturated copolymerisable radical having from 2 to 24carbon atoms which may be further substituted, W is a C₂-C₁₂alkyleneradical, phenylene radical or C₇-C₁₂aralkylene radical, each of R₄ andR₄′ independently of the other is hydrogen, C₁-C₄alkyl or halogen, R₅ isa bivalent aliphatic, cycloaliphatic, aliphatic-cycloaliphatic,aromatic, araliphatic or aliphatic-heterocyclic hydrocarbon radical, R₆is hydrogen or C₁-C₄alkyl, each of alk and alk′ independently of theother is a linear or branched C₁-C₁₂alkylene radical, each of m and nindependently of the other is the number 0 or 1, Z″ is C₁-C₆alkylene andP₁ independently is a radical of the above-mentioned formula (5) whereinQ₁ is a radical of the above formula (5a), (5b), (5c) or (5e) and nindependently is as defined above, or (iii) Q together with —NR—, —NR′,—NR, or —NR₁′ forms a cyclic ring of formula

 wherein each of R₄ and R₄′ independently of the other is as definedabove.
 3. A prepolymer according to claim 2, wherein Q is a radical offormula (5) wherein n is the number 0 and Q₁ is a radical of formula(5a) wherein m is 0, R₃ is a radical of formula

wherein p is the number 0 or 1, R₇ is hydrogen, C₁-C₄alkyl or halogen,each of R₈ and R₉ independently of the other is hydrogen, C₁-C₄alkyl,phenyl, carboxy or halogen, and Z′ is linear or branched C₁-C₁₂alkyleneor unsubstituted or C₁-C₄alkyl- or C₁-C₄alkoxy-substituted phenylene orC₇-C₁₂aralkylene.
 4. A prepotymer according to claim 2, wherein Q is aradical of formula (5) wherein n is the number 1 and Q₁ is a radical offormula (5a) wherein m is 1, R₃ is a radical of formula

wherein p is the number 0, R₇ is hydrogen or C₁-C₄alkyl, R₈ is hydrogen,methyl, chlorine or phenyl, R₉ is hydrogen or carboxy, and Z is linearor branched C₁-C₁₂alkylene.
 5. A prepolymer according to claim 1,wherein Q is a radical of formula

wherein R₅ is linear or branched C₆-C₁₀alkylene; cyclohexylene-methyleneor cyclohexylene-methylene-cyclohexylene each unsubstituted orsubstituted in the cyclohexyl moiety by from 1 to 3 methyl groups; orphenylene or phenylene-methylene-phenylene each unsubstituted orsubstituted in the phenyl moiety by methyl.
 6. A prepolymer according toclaim 5, wherein Q is a radical of formula 5′ or 5′″.
 7. A prepolymeraccording to claim 1, wherein A is a bivalent radical of formula (2a)wherein R and R′ are each hydrogen or C₁-C₄alkyl and A₁ is a bivalentpolyalkylene glycol radical of formula—Alk—[(O—CH₂—CH₂)_(r)—(O—CHR₁₀—CHR₁₁)_(s)]—O-Alk′-  (7a) wherein (Alk)and (Alk′) are identical and each is linear or branched C₂-C₆alkylene,one of the radicals R₁₀ and R₁₁ is hydrogen and the other is methyl, andeach of r and s independently of the other is a number from 0 to 80, thesum of (r+s) being from 2 to
 80. 8. A prepolymer according to claim 1,wherein A is a bivalent radical of formula (2a) wherein R and R′ areeach hydrogen and A₁ is a bivalent polyalkylene glycol radical offormula —Alk—(O—CH₂CH₂)_(r)—O-Alk′-  (7b) wherein (Alk) and (Alk′) areidentical and each is linear or branched C₂-C₄alkylene, and r is anumber from 4 to
 50. 9. A prepolymer according to claim 1, wherein A isa bivalent radical of formula (2a) wherein R and R′ are eachhydroxy-substituted C₁-C₄alkyl and A₁ is a C₂-C₆-alkylene radical.
 10. Aprepolymer according to claims 1, wherein T is a bivalent radical offormula (2) given in claim 1, wherein X is linear or branchedC₆-C₁₀alkylene; cyclohexylene-methylene orcyclohexylene-methylene-cyclohexylene each unsubstituted or substitutedin the cyclohexyl moiety by from 1 to 3 methyl groups; or phenylene orphenylene-methylene-phenylene each unsubstituted or substituted in thephenyl moiety by methyl.
 11. A prepolymer according claim 1, wherein Bis a radical of formula (2b) wherein each of R₁ and R₁′ independently ofthe other is hydrogen or C₁-C₄alkyl and B₁ is a radical of formula

wherein each of alk*, alk** and alk*** independently of the others is aC₂-C₁₂alkylene radical; I is the number 1 or 0 and each of R₂ and R₂′independently of the other has the meanings given in claim 1 for R₂. 12.A prepolymer of formula (1) according to claim 1, wherein Q is a radicalof formula

wherein R₅ is linear or branched C₆-C₁₀alkylene; cyclohexylene-methyleneor cyclohexylene-methylene-cyclohexylene each unsubstituted orsubstituted in the cyclohexyl moiety by from 1 to 3 methyl groups; orphenylene or phenylene-methylene-phenylene each unsubstituted orsubstituted in the phenyl moiety by methyl, and CP is a bivalentcopolymer fragment consisting of the segments A, B and T, wherein A is abivalent radical of formula (2a) wherein each of R and R′ independentlyof the other is hydrogen or C₁-C₄alkyl and A₁ is a radical of formula —Alk—[(O—CH₂—CH₂)_(r)—(O—CHR₁₀—CHR₁₁)_(s)]—O-Alk′—  (7a)  wherein (Alk)and (Alk′) are identical and each is linear or branched C₂-C₆alkylene,one of the radicals R₁₀ and R₁₁ is hydrogen and the other is methyl, andeach of r and s independently of the other is a number from 0 to 80, thesum of (r+s) being from 2 to 80; T is a bivalent radical of formula (2)given in claim 1, wherein X is linear or branched C₆-C₁₀alkylene;cyclohexylene-methylene or cyclohexylene-methylene-cyclohexylene eachunsubstituted or substituted in the cyclohexyl moiety by from 1 to 3methyl groups; or phenylene or phenylene-methylene-phenylene eachunsubstituted or substituted in the phenyl moiety by methyl; and B is aradical of formula (2b) wherein each of R₁ and R₁′ independently of theother is hydrogen, C₁-C₂alkyl or hydroxy-C₁—C₂alkyl and B₁ is a bivalentradical of formula

 wherein each of alk*, alk** and alk*** independently of the others is aC₂-C₁₂alkylene radical; I is the number 1 or 0, and each of R₂ and R₂′independently of the other is hydrogen; a radical Q wherein Q is asdefined above, or a radical of formula Q—CP′—  (4)  wherein Q is asdefined above and CP′ is a bivalent copolymer fragment independentlyconsisting of at least two of the above-mentioned segments A, B and T.13. A prepolymer of formula (1) according to claim 1, wherein Q is aradical of formula

and CP is a bivalent copolymer fragment consisting of the segments A, Band T, wherein A is a bivalent radical of formula (2a) wherein R and R′are each hydrogen and A₁ is a radical of formula—Alk—(O—CH2-CH2)r—O—Alk′—  (7b)  wherein (Alk) and (Alk′) are identicaland each is linear or branched C2-C4alkylene, and r is a number from 4to 50; T is a bivalent radical of formula (2) given in claim 1, whereinX is the radical of adiisocyanate, less the two isocyanato groups,selected from the group isophorone diisocyanate (IPDI),toluylene-2,4-diisocyanate (TDI), methylenebis(cyclohexyl isocyanate),1,6-diisocyanato-2,2,4-trimethyl-n-hexane (TMDI), methylenebis(phenylisocyanate), methylenebis(cyclohexyl isocyanate) and hexamethylenediisocyanate (HMDI); and B is a radical of formula (2b) wherein R₁ andR₁′ are each hydrogen and B₁ is a bivalent radical of formula

 wherein I is the number 0; each of alk* and alk** independently of theother is a C₂-C₆alkylene radical; and each of R₂ and R₂′ independentlyof the other is hydrogen; a radical Q wherein Q is as defined above, ora radical of formula Q—CP′—  (4)  wherein Q is as defined above and CP′is a bivalent copolymer fragment independently consisting of at leasttwo of the above-mentioned segments A, B and T.
 14. A process for thepreparation of a prepolymer of formula (1) according to claim 1, whichcomprises reacting together a compound of formula

a compound of formula  O═C═N—X—N═C═O  (11), and a compound of formula

wherein A₁, R, R′, R₁, R₁′ and X are each as defined in claim 1 and B₁′independently has the meanings given in claim 1 for B₁, except that R₂in the amine groups of formula (3) is in each case hydrogen, andreacting the copolymer so obtained of formula H—CP*—H  (1a), wherein CP*independently has the meanings given in claim 1 for CP, except that R₂in the segments B is hydrogen or a radical —CP′—NR″H, R″ independentlyhas the meanings given in claim 1 for R and CP′ is as defined in claim1, with a compound of formula Y—Q₁  (13), wherein Q₁ is a radical offormula

and wherein Z is linear or branched C₁-C₁₂alkylene, R₃ is anolefinically unsaturated copolymerisable radical having from 2 to 24carbon atoms which may be further substituted, W is a C₂-C₁₂alkyleneradical, phenylene radical or C₇-C₁₂aralkylene radical, each of R₄ andR₄′ independently of the other is hydrogen, C₁-C₄alkyl or halogen, R₅ isa bivalent aliphatic, cycloaliphatic, aliphatic-cycloaliphatic,aromatic, araliphatic or aliphatic-heterocyclic hydrocarbon radical, R₆is hydrogen or C₁-C₄alkyl, each of alk and alk′ independently of theother is a linear or branched C₁-C₁₂alkylene radical, m is the number 0or 1, Z″ is C₁-C₆alkylene and P1 independently is a radical of theformula

Q₁ is a radical of the above formula (5a), (5b), (5c) or (5e) and n isthe number 0 or 1, and Y is halogen, a carboxyl group —COOH; a carboxylgroup derivative or a group —N═C═O, or wherein Q₁ together with Y formsa heterocyclic compound.
 15. A prepolymer obtained by the processaccording to claim
 14. 16. A copolymer of formula H—CP*—H  (1a), whereinCP* independently has the meanings given in claim 1 for CP, except thatR₂ in the segments B is hydrogen or a radical —CP′—NR″H, R″independently has the meanings given in claim 1 for R and CP′ is asdefined in claim
 1. 17. A compound of formula

wherein R₅ is a bivalent aliphatic, cycloaliphatic,aliphatic-cycloaliphatic, aromatic, araliphatic oraliphatic-heterocyclic hydrocarbon radical, R₆ is hydrogen orC₁-C₄alkyl, each of alk and alk′ independently of the other is a linearor branched C₁-C₁₂alkylene radical, and P₁ is a radical of formula (5)given in claim 2, wherein Q₁ is a radical of formula (5a), (5b) or (5c)given in claim 2 and n is as defined in claim
 2. 18. A compound offormula

wherein R₆ is hydrogen or C₁-C₄alkyl, each of alk and alk′ independentlyof the other is a linear or branched C₁-C₁₂alkylene radical, and P₁ is aradical of formula (5) given in claim 2, wherein Q₁ is a radical offormula (5a), (5b) or (5c) given in claim 2 and n is as defined in claim2.
 19. A polymer obtained by crosslinking a prepolymer according toclaim 1, in the absence or presence of an additional vinyl comonomer.20. A polymer according to claim 19, obtained by photo-crosslinking aprepolymer according to claim 1 in the absence of an additional vinylcomonomer.
 21. A process for the preparation of a polymer according toclaim 19, which comprises photo-crosslinking a prepolymer accordingclaim 1 in the absence or presence of an additional vinyl comonomer. 22.A process according to claim 21, wherein the prepolymer is used insubstantially pure form.
 23. A process for the manufacture of mouldings,which comprises the following steps: a) introducing into a mould aprepolymer of formula (1) of claim 1 that is liquid at room temperatureor readily meltable and that is substantially free of solvents, in theabsence or presence of an additional vinyl comonomer and/orphotoinitiator, b) causing photo-crosslinking for a period of ≦60minutes, c) opening the mould so that the moulding can be removed fromthe mould.
 24. A process for the manufacture of mouldings, whichcomprises the following steps: a) preparing a substantially aqueoussolution of a water-soluble prepolymer of formula (1) of claim 1 in theabsence or presence of an additional vinyl comonomer and/orphotoinitiator, b) introducing the resulting solution into a mould, c)causing photo-crosslinking for a period of ≦60 minutes, d) opening themould so that the moulding can be removed from the mould.
 25. A processaccording to claim 23, wherein the moulding is a contact lens.
 26. Aprocess according to claim 24, wherein the moulding is a contact lens.27. A moulding obtained by the process according to claim
 23. 28. Amoulding obtained by the process according to claim 24.